Back up iron sights have existed for many years to provide a sturdy and purely mechanical method for aligning a shooter's line of vision with a bullet's trajectory. Over those years, advances have been made to increase the durability, aesthetics, and function of back up iron sights. The basic components of sights have stayed the same, namely an aperture in the rear of the gun to narrow the vision and provide the first point of alignment as well as a post in the front of the rifle to provide the second point of alignment with the target. When the eye, aperture, post, and target are all aligned in a line of sight, then the flight path of the bullet is determined and an effective shot can be made. A major factor in how well a shooter will perform is how intuitive sights are to align. If there are inconsistencies in the relative positions of the different sight components that result from range adjustments, wind adjustments, ammunition adjustment, or any other adjustment made to the front sight, then a shooter may become unconsciously biased by lining up components of the sight that are not intended to be aligned.
Frequently, front sight posts are protected with a surrounding housing, commonly referred to as “ears”, that prevents the post from being moved or damaged should the firearm be dropped or come into contact with foreign objects. This protective housing is not intended to create a line of sight on a state of the art front sight. However, the ears on this protective housing or tower provides an extra alignment point, which can improperly be relied upon by the shooter.
The front sight post must be adjusted for each individual rifle and readjusted to accommodate change in ammunition as well as many other factors if maximum accuracy is to be held. When the front sight is adjusted it changes position with respect to the ears of its protective housing, thereby changing what is seen when looking through the rear sight aperture. The ears surrounding the front sight post do not currently move along with the front sight post to provide continuous alignment. Only the sight post adjusts up and down while the protective ears remain in one position.
A standard sight picture will have two points of visual alignment. The first point that creates the alignment is the front sight post in the center of the rear aperture. The second, which is often incorrectly relied upon by the person aiming the firearm, would be the “ears” of the housing or apparatus that surrounds the sight post, depending upon the front sight, with the rear aperture. A person aiming the firearm often incorrectly relies on the position of the tower unconsciously, particularly if that person often shoots at a constant distance, as may occur at a shooting range.
Current systems typically utilize a front sight detent to ensure the front sight post does not move after adjustment. While effective at keeping the front sight post from moving, it increases the difficulty of adjusting the front sight. A special front sight adjustment tool or an improvised tool such as a bullet must be used to depress the detent, hindering the ability of the operator to turn the front sight post.